where to use the xdm host chooser?

[Rob]

Zhang Weiwu wrote:
> Rob wrote:
> 
>> Zhang Weiwu wrote:
>>
>>> Hello. Now I have my /usr/X11R6/lib/X11/xdm/Xaccess contain (only) this:
>>> *   CHOOSER BROADCAST
>>>
>>> according to xdm(1) this will enable XDMCP host chooser upon user 
>>> login. Now I reboot, xdm login box pops up, everything like it was 
>>> before.
>>
>>
>>
>> I think it means any host can connect and asks in a broadcast.
>> If, on your network, a host does
>>   X -broadcast
>> your machine will/may appear in the that machine's chooser list.
> 
> 
> I don't really get you, I'm a xdm newbie;)
> 
> I am not sure of the inner machenism but in my local network 
> (192.168.0.0/24) everyone in the office use gdm and turned on XDMCP, so 
> you pick up a box with gdm login screen, select 'run host chooser' from 
> 'system' menu, you will see all the computers in the office listed there 
> and I can pick up one to login. I believe this means they are all 
> broadcasting.
> 
>>
>> I don't know if it also allows an indirect request:
>>     X -indirect <your X host>
>>
>> Oh, and take also a note of this in xdm-config file:
>>
>> ! SECURITY: do not listen for XDMCP or Chooser requests
>> ! Comment out this line if you want to manage X terminals with xdm
>> DisplayManager.requestPort:     0
> 
> 
> What does this mean? I am running a slow box I don't need myself to be 
> listed in the host chooser of other boxes, but I need to be able to 
> login to other boxes.

I'm not an expert either, but I have some memories when I was fiddling
with X and xdm configuration. So take my advice was a pinch of salt.

The files /usr/X11R6/lib/X11/xdm/Xaccess and /usr/X11R6/lib/X11/xdm/xdm-config
are only for regulating access from other hosts to your PC. Apparently that's
not what you're interested in. For security reasons, it's then better to block
that access, since X is a rather insecure protocol.

So, if other computers are configured such that they answer broadcast requests,
or direct access request, you can simply type that from your PC.

You requesting a broadcast, should be something like:
	X -broadcast

If you want to get a chooser from a specific host, then type:
	X -indirect <host>

If you want to get directly to xdm on a specific host, then do:
	X -query <host>

At least that's what I remember. Do "X -help" for all flags, such
as forcing a display 3 and/or virtual terminal 9 ("X :3 vt9").

However, once again, I may be wrong here in the details. Hopefully a more
knowledgeable person will give comments too.

Regards,
Rob.